In an image from the upcoming May 10 episode of The CW's show, both Stefan's older brother and Klaus' sister look terrified of something unseen.

Damon and Rebekah are likely to be on the same side during one last battle in "The Vampire Diaries" season finale. As hinted in a new picture which is debuted via TV Guide, both the older Salvatore and the only daughter of the Original family are shocked and terrified of something or someone unseen in the final episode of the third season.

It's unclear what threatens Damon and Rebekah, but Steven R. McQueen has spilled that "there will be blood" in the upcoming May 10 outing. Meanwhile, executive producer Julie Plec said the episode will be an emotional one as it includes a flashback of Elena's past.

"It's just a really poignant, sweet and bittersweet reflection back to a time when life was so much simpler for all of our humans and former humans," she described the scenes that will feature the first appearances of Elena's adoptive parents (guest stars Jason MacDonald and Erin Beute). "I hope it turns out as well as we want it to because it's a really special episode."

Titled "The Departed", the season ender also promises to provide an answer to the ultimate question of Elena's choice between Damon and Stefan. "It will not be easy. It will be very emotional for both sides because it's going to be a very honest, very pure, very difficult decision," Plec dished on the highly anticipated moment.